1. Field of the Invention
The present invention relates to a hand-held rivet nut (rivet bolt) tool, and more particularly to a hand-held rivet nut (rivet bolt) tool having a quick-change mandrel that reduces manufacturing time and costs, also offering a solution to solve the headache problem of rivet nut (rivet bolt) jammed with the mandrel.
2. Description of the Related Art
A hand-held rivet nut (rivet bolt) tool is adapted to set rivet nuts (rivet bolts) in a work piece. With reference to FIGS. 8 and 9, a conventional hand-held rivet nut tool disclosed in U.S. Pat. No. 5,729,880 comprises a body 60, an operating handle 61, a sleeve 70 and a mandrel 80. The operating handle 61 is pivotally connected to the body 60. The sleeve 70 is movably mounted through the body 60, is actuated by the operating handle 61 and has a threaded hole 71 extending radially therethrough for receiving a ball 72, a spring 73 and a bolt 74. The spring 73 urges the ball 72 so that the ball 72 partially protrudes from an inner surface of the sleeve 70. The mandrel 80 is rotatably mounted through the sleeve 70 and includes an outer surface, a front threaded portion 81 and an annular groove 82. The front threaded portion 81 is provided with an external thread. The annular groove 82 is fonned in the outer surface of the mandrel 80 and corresponds to the ball 72. The spring 73 forces the ball 72 into engagement with the annular groove 82 to hold the mandrel 80 in position in the sleeve 70. In operation, a rivet nut 90 is screwed onto the front threaded portion 81 of the mandrel 80 and is then inserted into a predrilled hole in a work piece. Afterward the operating handle 61 is pushed to move the sleeve 70 and mandrel 80 rearward. The moving mandrel 80 pulls the rivet nut 90 so that the rivet nut 90 is then defonned and is set in a work piece. After the rivet nut 90 is set, the mandrel 80 is rotated to screw out of the rivet nut 90.
The holding structure between the mandrel 80 and sleeve 70 as described above is a quick-change structure. Therefore, mandrels 80 of different thread sizes can be quickly interchanged to conform to rivet nuts 90 of different thread sizes. However, the manufacturing process of such holding structure is complicated because it comprises steps of drilling and tapping the threaded hole 71, putting the ball 72 and spring 73 into the threaded hole 71 and then screwing the bolt 74 into the threaded hole 71, which decreases production efficiency and increases manufacturing time and costs. Moreover, the ball 72 engages the annular groove 82 only at a point. The area of engagement between the ball 72 and annular groove 82 is too small so that the mandrel 80 may become accidentally disengaged. Furthermore, when the rivet nut 90 is jammed on the mandrel 80, the work piece or rivet nut tool must be destroyed in order to take out the jammed rivet nut 90, thus causing huge inconvenience.
To overcome the shortcomings, the present invention provides a hand-held rivet nut (rivet bolt) tool with quick-change mandrel to mitigate or obviate the aforementioned problems.